The instant invention relates to document feeding apparatus, and more particularly to a modular drive unit removably housed in such feeding apparatus.
Mechanisms for the feeding of paper documents generally fall into two categories, those being vacuum fed and friction fed. The following description of the prior art will deal only with those types of feeders and material handlers which are considered to be friction-type feeders and which include singulators.
Friction feeders are preferred when it comes to feeding single paper documents. Friction feeders, as the name implies, rely on the interaction of several components that result in the singulation of paper documents. Two methods of singulation are provided by friction feeders. One style is via top feed and the second style is via bottom feed. A friction feeder is designed to operate as a top feed or a bottom feed, but it cannot operate in both modes. The components are usually a drive roller and a retarding device. The retarding device is of a material which provides a high coefficient of friction between the paper being fed and the drive roller.
In a bottom feed configuration, the paper begins as a vertical stack placed on a plurality of belts which usually are supported by a feeder table. This plurality of belts then advance the stack of paper toward a retarding device. As the plurality of belts advance the stack of paper under the retarding device, the friction between the belts and the bottom of the stack of paper tends to pull paper off the bottom of the stack. The retarding device provides the friction that acts to hold back the stack of paper. Therefore, the number of paper documents that are pulled from the bottom of the vertical stack is determined by the physical distance between the belts and the retarding device. If the distance is substantially the thickness of a single piece of paper, or the thickness of the material being singulated, a single paper will be delivered from the bottom of the stack. The single sheet delivery is generally the desired result. If the distance between the belts and the retarding device is the thickness of several pieces of paper or of the documents to be singulated, then a stream of paper documents will be delivered from the stack.
The drive system for friction feeders generally is run off a main drive for the document feeding system of which the friction feeder is a component. A substantial number of belts, pulleys and clutches are typically employed to drive the friction feeder. In operation, it is not uncommon for the friction feeder drive to develop problems, which can cause lengthy shutdowns of the friction feeders and document feeding system. Moreover, it is a time consuming effort to repair the friction feeder drive because of its connection to the main drive for the document feeding system. Moreover, the prior art drive systems are so remote from the effecting feed belts and rotating members that deflections and other undesirable effects are introduced to the feeding components.
Accordingly, the instant invention provides a modular drive unit for a document feeder which can be easily removed for effecting repairs thereto without involving the drive system for the document feeding system, and because of its stability does not introduce deflections and other undesirable effects to the feeding components. Moreover, it is possible to replace the drive unit with a different type if so desired.